Hey Guys,
I had the same issue and did come up with a resolution. I have a 2019 Ram Laramie Longhorn in which the 12" display would not turn on. I tried the reset holding the volume/power button and tuner button down for 20 seconds but that did nothing. I tried disconnecting the Bluetooth and various other internet solutions which did not work. Ultimately, what ended up working was pulling the fuses in which I thought were to the display. For a list of the fuses and their description and location, use this link;
RAM 1500 5th-Gen External and Internal Power Distribution Centers - Google Drive . I wasn't exactly sure which fuse was the right one based off of the descriptions so i pulled fuses F12, F24, F26, F27, and F44 and let the truck sit for 5 hours to allow time for any internal capacitors or batteries to die intentionally. After the 5 hours passed, i plugged the fuses back in (making sure they weren't blown first) and when I started my truck up, the display came right on. It was back to the factory settings but I could live with that. I would imagine disconnecting the battery would achieve the same result but you do in fact have a blown fuse, you'll never know. Ultimately, getting to the fuse box is easy. It is located under the steering column, has about 8 snap connectors and two 7mm screws that need to be removed.
Hope this helps!